{
  "lesson": "21-tool-registry-schema-validation",
  "title": "Tool Registry with Schema Validation",
  "questions": [
    {
      "stage": "pre",
      "question": "Why register a tool's schema separately from its handler?",
      "options": [
        "Because handlers cannot return JSON",
        "So the validator stays pure data, and the handler stays opaque code",
        "Because schemas must be compiled",
        "Because schemas have to live in YAML"
      ],
      "correct": 1,
      "explanation": "Keeping the schema as data and the handler as code lets the validator be a pure function over the schema tree."
    },
    {
      "stage": "check",
      "question": "Which keywords are intentionally outside the subset this lesson implements?",
      "options": [
        "items, enum",
        "oneOf, anyOf, $ref, allOf",
        "minLength, maxLength, pattern",
        "type, properties, required"
      ],
      "correct": 1,
      "explanation": "The omitted keywords add cycles and reference resolution. We keep the subset linear so the validator stays a single recursive walk."
    },
    {
      "stage": "check",
      "question": "Why does register() reject duplicates by default?",
      "options": [
        "Because the schema cannot be re-validated",
        "Silent overwrites are the cause of production tool catalog drift",
        "Because the registry cannot store more than one record per name",
        "Because handlers cannot be replaced"
      ],
      "correct": 1,
      "explanation": "Forcing override=True surfaces the case where two parts of the code intend to own the same tool name."
    },
    {
      "stage": "check",
      "question": "What does the validator do when a schema specifies type integer but receives the value True?",
      "options": [
        "Coerces to integer silently",
        "Treats it as 1 and passes",
        "Raises an unhandled exception",
        "Returns a type error because bool is not integer in this validator"
      ],
      "correct": 3,
      "explanation": "Python bool is a subclass of int, but the validator filters bool out of the integer check. JSON booleans and integers are distinct."
    },
    {
      "stage": "post",
      "question": "When the input object is {'user': {'email': 0}} and the schema requires user.email to be a string, what is the error path?",
      "options": [
        "/user",
        "/user/email",
        "/",
        "user.email"
      ],
      "correct": 1,
      "explanation": "JSON pointer encodes the descent through user then email as /user/email."
    },
    {
      "stage": "post",
      "question": "Why is the registry not a security boundary?",
      "options": [
        "Because handlers are async",
        "Because handlers can still misbehave after validation passes",
        "Because the registry is in-process",
        "Because the schema is JSON"
      ],
      "correct": 1,
      "explanation": "The registry checks shape. Behavior, timeouts, and isolation belong to the dispatcher and the sandbox."
    }
  ]
}